The power of the federal government to address foreign trade is generally a foregone, and unchallenged, conclusion, and the "Indian Tribes" were so quickly marginalized that it is mostly the second aspect of this clause (sometimes taken on its own as the "Interstate Commerce Clause") that has drawn attention over the years.

The original intent of this clause, as laid out by James Madison in Federalist #42, was to prevent the states, especially the Atlantic states with seaports through which foreign trade passed to other states, from establishing import/export tariffs, transport tolls, or protectionist policies on their own, at the expense of the other states - yet another oversight, in the eyes of federalists at least, of the Articles of Confederation to be remedied in the new Constitution.

The Commerce Clause saw its first major appearance in court in 1824 with Gibbons v. Ogden, in which the Supreme Court ruled that New York could not grant a ferry service a monopoly on transportation to New Jersey, as this represented a matter of interstate commerce which was properly the domain of the federal government. Following this was a long period of overall silence on the matter, reflective of a government that rarely invoked the clause and of a nation which, in the tense leadup to the American Civil War, tried to avoid the inflammatory issue of the federal government attempting to control the economic activities of the states.

After the war, the Commerce Clause maintained a low profile, showing up in 1895's U.S. v. E.C. Knight Co. for the ruling that manufacturing did not in fact qualify as commerce or trade, and thus some attempted government actions under the Sherman Antitrust Act were not constitutionally justified. While it did show up in other cases of the time, its next important showing, and arguably its last great hurrah, was in 1918's Hammer v. Dagenhart, in which the court rejected the establishment of de facto national child labor laws for factories as a matter entirely internal to the states and thus removed from national purview. Even here, however, the majority opinion seems on the balance favorable towards the intent of the drafters of the law, and references prior cases in which the court had read the Commerce Clause to allow similar federal regulation, as with the Pure Food and Drug Act of 1906.

Here, for those who favor a more limited national government, is where it all starts to go to pot. As recently as 1936, in Carter v. Carter Coal, the Supreme Court rejected coal mining as a viable subject for labor regulation, again noting it as an intrastate concern. This was, of course, part of a series of cases in which treasured elements of PresidentFranklin D. Roosevelt's favored "New Deal" were declared unconstitutional. In 1936, Roosevelt was reelected with a sense of mandate, and attempted to pack the Supreme Court with more favorable justices. The plan was tied up in Congress and would have probably failed anyway, but was apparently enough leverage to force the Supreme Court into submission, reversing its opposition on several matters, the Commerce Clause among them. In 1937's National Labor Relations Board v. Jones & Laughlin Steel Corp. the court abandoned the distinction between production and commerce, and moved towards a more expansive understanding of what defines "interstate commerce", and with United States v. Darby in 1941 reversed its Hammer ruling, allowing national labor regulation.

This trend continued and arguably reached its apex in Wickard v. Filburn in 1949, in which a complaint against a farmer growing crops for his own consumption in excess of Agricultural Adjustment Act quotas was found actionable, more or less on the grounds that the grain he grew would otherwise have been purchased from another producer in the national market. With this case came the birth of the doctrine that anything which "exerts a substantial economic effect on interstate commerce" fell under the aegis of the Commerce Clause. As the case itself demonstrates, that "substantial economic effect" could and would be read fairly liberally.

As settled law, the Commerce Clause didn't make many major showings immediately afterwards, aside from perhaps 1964's Heart of Atlanta Motel v. United States, which used it as one basis to legitimize the imposition of nationwide desegregation. As the New Deal and successor movements progressed, arguably for upwards of 40 years, the Commerce Clause was invoked, along with the Necessary and Proper, or "elastic" and general welfare clauses, on a regular basis to justify actions of the federal government not otherwise specifically sanctioned in the Constitution, in what many critics saw as a repudiation of the Tenth Amendment. Most national economic regulations, from pollution controls to the minimum wage, rely on this somewhat loose interpretation to affirm their constitutionality.

However, the pendulum swings both ways, and the Supreme Court, in keeping with a recent shift away from New Deal-era judicial thought and towards a strengthened federalism, has recently taken steps towards reigning in the loose contemporary interpretation of the clause, since 1995 striking down the Gun Free School Zones Act, and as noted in Supreme Court logic, portions of the Violence Against Women Act, both examples of Congress using the clause to claim federal dominion over matters only tenuously interpretable as commerce. Justice Thomas's concurring opinion in U.S. v. Lopez, the former case, argues that the Commerce Clause has been read far too expansively in recent years, and goes as far as to suggest a major overhaul or abandonment of the substantial effects doctrine. As more and more of the judiciary comes to be made up of appointees from after the complete collapse, in the early 1980s, of the great Democratic New Deal Coalition, and the influence of conservative judicial movements like the Federalist Society grows, his suggestions may gain purchase and this trend towards a more constricting interpretation may well continue or accellerate. The possibility of an upcoming attempt at "tort reform" at the national level would be likely to bring up a series of interesting Commerce Clause questions, and may serve as the backdrop to a major reconceptualizing of the clause's implications for modern-day law.